EP0130670A1 - Fluiddruck-Fühlergerät - Google Patents

Fluiddruck-Fühlergerät Download PDF

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Publication number
EP0130670A1
EP0130670A1 EP84302881A EP84302881A EP0130670A1 EP 0130670 A1 EP0130670 A1 EP 0130670A1 EP 84302881 A EP84302881 A EP 84302881A EP 84302881 A EP84302881 A EP 84302881A EP 0130670 A1 EP0130670 A1 EP 0130670A1
Authority
EP
European Patent Office
Prior art keywords
strain gauge
resilient
delivery tube
output signals
fluid pressure
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP84302881A
Other languages
English (en)
French (fr)
Inventor
Peter G. Wheeldon
John Kent
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Peritronic Medical Ind PLC
Original Assignee
Peritronic Medical Ind PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Peritronic Medical Ind PLC filed Critical Peritronic Medical Ind PLC
Publication of EP0130670A1 publication Critical patent/EP0130670A1/de
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
    • G01L9/0001—Transmitting or indicating the displacement of elastically deformable gauges by electric, electro-mechanical, magnetic or electro-magnetic means
    • G01L9/0002—Transmitting or indicating the displacement of elastically deformable gauges by electric, electro-mechanical, magnetic or electro-magnetic means using variations in ohmic resistance
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
    • G01L9/02—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means by making use of variations in ohmic resistance, e.g. of potentiometers, electric circuits therefor, e.g. bridges, amplifiers or signal conditioning
    • G01L9/04—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means by making use of variations in ohmic resistance, e.g. of potentiometers, electric circuits therefor, e.g. bridges, amplifiers or signal conditioning of resistance-strain gauges

Definitions

  • the present invention relates to fluid pressure sensing apparatus and, more particularly, to such apparatus for monitoring fluid pressure within the delivery tube of a medical infusion pump or for use in other applications where there is a requirement for monitoring fluid pressure within a fluid flow tube without permitting direct access to the fluid flow, itself.
  • a medical infusion pump for example, which operates on a peristaltic principle and applies a peristaltic pumping action to the resilient walled delivery tube of a simple intraveneous infusion set
  • fluid delivery under pressure is achieved without violating the sterile barrier maintained internally within the infusion set.
  • a pressure limiting facility in order to protect the patient and the infusion system from excessive pressure build-up in the delivery tube downstream of the pump, in the event of an occlusion or other blockage occurring.
  • Such a facility requires apparatus for sensing or monitoring pressure within the delivery tube without, again, violating the sterile barrier represented by the tube and it is an object of the present invention to provide such apparatus.
  • the invention consists in apparatus for sensing fluid pressure within a fluid delivery tube, comprising resilient means for engaging the delivery tube, a strain gauge device coupled to the'resilient means to detect deflection or distortion thereof in response to fluid pressure within the tube, and means for processing output signals produced by the strain gauge device and providing data corresponding to the fluid pressure within the delivery tube.
  • the resilient means may comprise a resilient member, to which the strain gauge is affixed, disposed in spaced relation with a rigid surface, the spacing being such that the delivery tube is slightly flattened or distorted when engaged between the resilient member and rigid surface.
  • the resilient means is a channel-shaped device having opposed resilient and rigid side walls.
  • it may be a channel-shaped member made from resilient material and having the strain gauge affixed to the underside of its external surface.
  • the apparatus may be calibrated so that the data produced by the processing means provides an indication of the pressure distorting the resilient member.
  • the processing means may be adapted to produce an alarm signal when the processing means establishes that an output signal from the strain guage differs from a predetermined value or falls outside predetermined limits.
  • the invention is particularly suitable for sensing pressure changes within a fluid delivery tube and producing an alarm signal when the detected pressure falls outside predetermined limits.
  • the processing means may comprise storage means for storing reference data corresponding to an initial or datum output signal produced by the strain gauge and comparator means for comparing data corresponding to subsequent output signals from the strain gauge with the reference data and initiating an alarm signal whe1 the subsequent data differs from the reference data by more than a predetermined value.
  • the alarm signal may be an audio and/or visual alarm signal.
  • the visual alarm may comprise a digital display for displaying information corresponding to output signals produced by the strain gauge.
  • the apparatus In the case where the apparatus is arranged to sense pressure changes, it may accommodate a range of different tube sizes because the only information required relates to pressure change rather than absolute pressure. Any variation in the initial distortion of the resilient means owing to different tube sizes is immaterial.
  • the apparatus includes a channel-shaped device 1 which comprises a resilient side wall la, made from spring steel or other similar resilient material, and a rigid side wall 1b connected to the resilient side wall, in opposed spaced relation therewith, by means of a rigid spacer bar lc which is disposed between mutually adjacent edges of the two side walls and to which the two walls are fixed ,by suitable fastening means, such as, screws ld.
  • the side walls la,lb are arranged to embrace a portion of a flexible or resilient walled delivery tube 2 loaded into a peristaltic pump (not shown), at a position downstream of the pump head.
  • the spacing of the side walls la,lb is such that, when the delivery tube is fitted into the channel device, the portion embraced by the side walls fits snugly between the arms and is slightly flattened or distorted. Conversely, the resilient side wall 1a is slightly deflected. Hence, the tube 2 is gripped by the side walls of the channel device and is retained in this position during a pumping operation.
  • the channel device 1 is so mounted that the resilient side wall 1a is free to deflect under the action of the fluid pressure within the tube 2 without interference.
  • it may be associated with tube guides housed within the peristaltic pump.
  • a strain gauge 7 Bonded to the external surface of the resilient side wall la of the channel device, in a zone overlapping the marginal portion of the side wall la fastened to the spacer bar Ic, is a strain gauge 7 which is connected to a strain gauge bridge circuit 4 of electronic control circuitry for the system, via a termainal block 5 fastened to the side wall la.
  • the output of the strain gauge bridge 4 is connected to an amplifier 6 which is connected to one of the plurality of inputs of an analogue multiplexer 7 having its output connected to an analogue-to-digital (A/D) converter 8.
  • a microprocessor 9 conveniently, an 8-bit microprocessor, such as that marketed by RCA Inc. under the Model No.
  • .CDP 1806 Ace is interconnected with the multiplexer 7 and the A/D converter 8 via a control bus 10 and an 8-bit data bus 11.
  • the latter also interconnect the microprocessor with alarm logic and digital display circuitry 12,13.
  • the alarm logic circuit 12 is connected to control an audio alarm 14 and a visual alarm indication associated with the digital display 13.
  • a standing resistance is produced in the strain gauge 3 owing to the deflection of the side wall la by the tube which is, itself, slightly flattened.
  • the resulting output signal from the strain gauge bridge 4 is amplified and sampled by the microprocessor 9 which switches the amplifier output through the multiplexer 7 to the A/D converter 8.
  • the digital signal produced by the converter 8 is supplied to the microprocessor via the data bus 11 and is stored in the memory of the microprocessor as a reference datum against which future sample readings taken during operation of the pump are compared.
  • the resilient side wall la of the channel device 1 is either flexed outwardly or restores inwardly and these changes are registered in the output signal from the strain gauge bridge circuit 4.
  • An occlusion or partial occlusion of the delivery tube 2 causes outward deflection of the side wall la resulting in a change of strain gauge resistance and variation of the bridge circuit output signal.
  • the microprocessor 9 samples the various inputs to the multiplexer 7 and, at the next sampling of the amplifier output, the change in digital output signal from the A/D converter 8 is compared with the reference datum or information stored in the microprocessor memory and, if the variation between the two values exceeds preset limits also stored in the microprocessor memory, the microprocessor signals the alarm logic 12 which operates the audio alarm 14 and causes a visual alarm signal to be displayed on the digital display 13 to attract the attention of the pump operator.
  • the microprocessor 9 also supplied fluid pressure information to the digital display, via the data bus, in order to provide a visual display of fluid pressure information.
  • the multiplexer 7 permits the use of a sequence sampling system and the microprocessor 9 can interrogate the output of the A/D converter 8 for access to different information supplied to the various inputs of the multiplexer, thus keeping cost and component parts to a minimum through the multipurpose use of the same circuits.
EP84302881A 1983-04-27 1984-04-27 Fluiddruck-Fühlergerät Withdrawn EP0130670A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB838311528A GB8311528D0 (en) 1983-04-27 1983-04-27 Fluid pressure sensing apparatus
GB8311528 1983-04-27

Publications (1)

Publication Number Publication Date
EP0130670A1 true EP0130670A1 (de) 1985-01-09

Family

ID=10541803

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84302881A Withdrawn EP0130670A1 (de) 1983-04-27 1984-04-27 Fluiddruck-Fühlergerät

Country Status (3)

Country Link
EP (1) EP0130670A1 (de)
JP (1) JPS59224533A (de)
GB (1) GB8311528D0 (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2609953A1 (fr) * 1987-01-27 1988-07-29 Kelsey Hayes Co Procede et dispositif pour l'essai du systeme de freinage anti-blocage d'un vehicule
EP0283524A1 (de) * 1987-02-11 1988-09-28 Kistler Instrumente AG Verfahren und Anordnung zum Messen von Drücken in rohrförmigen Körpern
WO1990011501A1 (en) * 1989-03-28 1990-10-04 Claren Jan Control device for fluid containers of flexible material
US6696964B1 (en) 1999-08-24 2004-02-24 Crafcare Ab Device for monitoring the filling of a bag
GB2469820A (en) * 2009-04-28 2010-11-03 Haemair Ltd Fluid Pressure Sensing Device

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2038771B2 (de) * 1969-08-04 1975-11-27 The Bendix Corp., Southfield, Mich. (V.St.A.) Druck -MeBwertwandler
GB2007844A (en) * 1977-11-10 1979-05-23 Goodwood Data Systems Ltd Diesel fuel pipe transducer
EP0010584A1 (de) * 1978-10-19 1980-05-14 International Business Machines Corporation Vorrichtung zur Drucküberwachung
US4290311A (en) * 1980-02-08 1981-09-22 The United States Of America As Represented By The United States Department Of Energy Dilatometer

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2038771B2 (de) * 1969-08-04 1975-11-27 The Bendix Corp., Southfield, Mich. (V.St.A.) Druck -MeBwertwandler
GB2007844A (en) * 1977-11-10 1979-05-23 Goodwood Data Systems Ltd Diesel fuel pipe transducer
EP0010584A1 (de) * 1978-10-19 1980-05-14 International Business Machines Corporation Vorrichtung zur Drucküberwachung
US4290311A (en) * 1980-02-08 1981-09-22 The United States Of America As Represented By The United States Department Of Energy Dilatometer

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2609953A1 (fr) * 1987-01-27 1988-07-29 Kelsey Hayes Co Procede et dispositif pour l'essai du systeme de freinage anti-blocage d'un vehicule
EP0283524A1 (de) * 1987-02-11 1988-09-28 Kistler Instrumente AG Verfahren und Anordnung zum Messen von Drücken in rohrförmigen Körpern
WO1990011501A1 (en) * 1989-03-28 1990-10-04 Claren Jan Control device for fluid containers of flexible material
US5260692A (en) * 1989-03-28 1993-11-09 Crafcontrol Ab Control device for fluid containers of flexible material
US6696964B1 (en) 1999-08-24 2004-02-24 Crafcare Ab Device for monitoring the filling of a bag
GB2469820A (en) * 2009-04-28 2010-11-03 Haemair Ltd Fluid Pressure Sensing Device

Also Published As

Publication number Publication date
JPS59224533A (ja) 1984-12-17
GB8311528D0 (en) 1983-06-02

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Inventor name: KENT, JOHN

Inventor name: WHEELDON, PETER G.